Refactor WifiDataProviderChromeOs to implement WifiDataProviderImplBase directly.

content/browser/geolocation/wifi_data_provider_chromeos.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Provides wifi scan API binding for chromeos, using proprietary APIs.
 
 #include "content/browser/geolocation/wifi_data_provider_chromeos.h"
 
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
 #include "chrome/browser/chromeos/cros/network_library.h"
+#include "content/browser/browser_thread.h"
 
 namespace {
 // The time periods between successive polls of the wifi data.
 const int kDefaultPollingIntervalMilliseconds = 10 * 1000;  // 10s
 const int kNoChangePollingIntervalMilliseconds = 2 * 60 * 1000;  // 2 mins
 const int kTwoNoChangePollingIntervalMilliseconds = 10 * 60 * 1000;  // 10 mins
 const int kNoWifiPollingIntervalMilliseconds = 20 * 1000; // 20s
 }
 
 namespace chromeos {
@@ skipping 43 matching lines @@
 }
 
 }  // namespace
 }  // namespace chromeos
 
 template<>
 WifiDataProviderImplBase* WifiDataProvider::DefaultFactoryFunction() {
   return new WifiDataProviderChromeOs();
 }
 
-WifiDataProviderChromeOs::WifiDataProviderChromeOs() {
+WifiDataProviderChromeOs::WifiDataProviderChromeOs() :
+    started_(false),
+    ALLOW_THIS_IN_INITIALIZER_LIST(task_factory_(this)) {
 }
 
 WifiDataProviderChromeOs::~WifiDataProviderChromeOs() {
 }
 
+bool WifiDataProviderChromeOs::StartDataProvider() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

[bulach, 2011/03/15 18:37:51]

hmm, not sure this would work.. afaict, this would run on the Geolocation
thread, right?

if I followed the chain correctly:
GeolocationProvider is a thread, it creates the GeolocationArbitrator in its
Init() method, and then on GeolocationArbitrator::OnAccessTokenStoresLoaded
it'll create the NewNetworkLocationProvider?

this check would then fail.. (similarly for the other methods...).

I think it's ok to remove these checks, and then only do the thread bouncing on
DoWifiScanTask / a couple of helper methods?

[stevenjb, 2011/03/16 01:06:26]

As bulach@ suggests, this CHECK gets triggered on ChromeOS.

+  DCHECK(!started_);
+  started_ = true;
+
+  wlan_api_.reset(NewWlanApi());
+  if (wlan_api_ == NULL) {
+    // Error! Can't do scans, so don't try and schedule one.
+    is_first_scan_complete_ = true;
+    return false;
+  }
+
+  DCHECK(polling_policy_ == NULL);
+  polling_policy_.reset(NewPollingPolicy());
+  DCHECK(polling_policy_ != NULL);
+
+  // Perform first scan ASAP regardless of the polling policy. If this scan
+  // fails we'll retry at a rate in line with the polling policy.
+  ScheduleNextScan(0);
+  return true;
+}
+
+void WifiDataProviderChromeOs::StopDataProvider() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  started_ = false;
+  wlan_api_.reset();
+  polling_policy_.reset();
+}
+
+bool WifiDataProviderChromeOs::GetData(WifiData *data) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  *data = wifi_data_;
+  return is_first_scan_complete_;
+}
+
 WifiDataProviderCommon::WlanApiInterface*
     WifiDataProviderChromeOs::NewWlanApi(chromeos::NetworkLibrary* lib) {
   return new chromeos::NetworkLibraryWlanApi(lib);
 }
 
 WifiDataProviderCommon::WlanApiInterface*
     WifiDataProviderChromeOs::NewWlanApi() {
   chromeos::CrosLibrary* cros_lib = chromeos::CrosLibrary::Get();
   DCHECK(cros_lib);
   if (!cros_lib->EnsureLoaded())
     return NULL;
   return NewWlanApi(cros_lib->GetNetworkLibrary());
 }
 
 PollingPolicyInterface* WifiDataProviderChromeOs::NewPollingPolicy() {
   return new GenericPollingPolicy<kDefaultPollingIntervalMilliseconds,
                                   kNoChangePollingIntervalMilliseconds,
                                   kTwoNoChangePollingIntervalMilliseconds,
                                   kNoWifiPollingIntervalMilliseconds>;
 }
+
+void WifiDataProviderChromeOs::DoWifiScanTask() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  bool update_available = false;
+  WifiData new_data;
+  if (!wlan_api_->GetAccessPointData(&new_data.access_point_data)) {
+    ScheduleNextScan(polling_policy_->NoWifiInterval());
+  } else {
+    update_available = wifi_data_.DiffersSignificantly(new_data);
+    wifi_data_ = new_data;
+    polling_policy_->UpdatePollingInterval(update_available);
+    ScheduleNextScan(polling_policy_->PollingInterval());
+  }
+  if (update_available || !is_first_scan_complete_) {
+    is_first_scan_complete_ = true;
+    NotifyListeners();
+  }
+}
+
+void WifiDataProviderChromeOs::ScheduleNextScan(int interval) {
+  MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      task_factory_.NewRunnableMethod(&WifiDataProviderChromeOs::DoWifiScanTask),

[bulach, 2011/03/15 18:37:51]

nit: >80cols

+      interval);

[stevenjb, 2011/03/16 01:06:26]

I'm still unfamiliar with Chrome threading, but is it possible / does it make
any sense to issue DoWifiScanTask from the UI thread there?

+}